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Question

What are your thoughts on district thermal energy?

Gareth  Young's picture
CEO Community Development of Community Energy Ltd

My background is twenty years at consultant Arups working on many energy related projects around the world. My technical background is a HNC qualified mechanical engineer (but that was many...

  • Member since 2021
  • 4 items added with 388 views
  • Nov 10, 2021
  • 388 views

Much talk and some action going on regarding so called 5th generation district thermal energy systems, mainly based on heat pumps. At present, the rival seems to be hydrogen, maybe using the existing methane piping net. I would be very interested in any thoughts or comments on this.

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Hi Gareth: Not sure why one would need to worry about a fuel source when thinking about District heating and cooling systems.  Numerous examples exist where ground loop geothermal and solar thermal do a very good job of providing the heat differential necessary to fully support a district system.  Many college campuses and commercial districts are active users of these alternate heating and cooling systems.  Solar thermal is very good at driving chillers, and supporting a four pipe system that handles both heating and cooling.  The challenge we face is the lack of knowledge and basic inertia that prevents a more active uptake of these alternate renewable energy technologies. If one is lucky enough to be located in proximity to a volcanic based geothermal source all the better, but active hot rocks are not widely available.  One day as our drilling technology gets better we will be able to sink really deep wells that can take advantage of the energy available deep in the Earth.

Gareth  Young's picture
Gareth Young on Nov 16, 2021

The big issues inhibiting it’s widespread uptake in the U.K. can be summarised as, 1). Many years of cheap gas-folk don’t want to change. 2) incredibly bad commercial contracts on the few projects that have gone ahead, locking consumers into long term contracts. 3) government imposed tariffs on electricity. 3) Planning laws which make it very difficult to get planning permission for large district thermal energy systems. There are others, but not worth mentioning here.

 

best

 

Gareth

 

the good news is that, following recent gas wholesale price rise’s people are at least talking about it.

Gareth, until green hydrogen is proven practical and price-competitive, it's safe to assume hydrogen-as-fuel is no more than a cynical ploy to increase sales of fossil fuel methane (95% of hydrogen is manufactured by steam-reforming methane). Because copious quantities of CO2 are released during steam reformation, burning hydrogen manufactured from it is even less "green" than burning the methane from which it's made.

Whether heat pumps can serve to provide a practical source of on-demand energy is questionable. Some full-scale prototypes would provide data to help determine whether it's practical.
Like other improvements in energy efficiency district heating is a laudable goal, and in urban areas can be effective. Time will tell whether it will make a significant contribution to the fight against climate change.

Gareth  Young's picture
Gareth Young on Nov 10, 2021

Very comprehensive answer. Thanks.

Evidence is starting to emerge from a few demonstration projects. London Southbank University has installed a relatively small 5th generation district thermal energy system. Professor Andy Ford of LSBU is one of the project originators. I have read online of a demonstration project in Germany claiming an annual COP of 5.9:1. 

 

Massive remaining issues remain to be solved before the large scale up-take of electricity driven heat pumps can happen. I’m told by HV electrical engineers that the overhead HV grid may be ok but the LV underground cables would have to be upgraded.

Bob Meinetz's picture
Bob Meinetz on Nov 15, 2021

In the U.S., Princeton University is probably farthest along on the development curve with heat pumps in its campus facilities.

That a university with a multi-$billion endowment might actually succeed in reaching "net-zero" status doesn't mean much, however, for weaning the bulk of humanity from fossil fuels. Anecdotal evidence from residential users in the U.S., who live in areas of moderate temperature gradients, report it can take 2-1/2 hours to dry a single load of clothes in a heat-pump-powered clothes dryer. Then, a wait of hours for water in the heat pump to be warmed again by convection, to start the next load.

If heat pumps at Princeton are more effective at easing climate guilt among wealthy patrons than replacing natural gas and coal power plants, they're the last thing we need at this stage of the game.

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